Linked Life Data

8366128

Source:http://linkedlifedata.com/resource/pubmed/id/8366128

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
1993-10-7
pubmed:abstractText
Previous NMR studies (Karslake, C., Piotto, M. E., Pak, Y. M., Weiner, H., and Gorenstein, D. G. (1990) Biochemistry 29, 9872-9878) had shown that a 22-amino acid signal peptide of rat liver aldehyde dehydrogenase (ALDH) when bound to a micelle had two amphiphilic alpha-helices, one located at the N terminus and the other at the C terminus. It was shown that deletion of either helix caused the precursor protein not to be imported (Wang, Y., and Weiner, H., (1993) J. Biol. Chem. 268, 4759-4765). The two helices are separated by a Arg-Gly-Pro flexible "linker" region, and to test the role of this linker region in the import and processing of the precursor protein, we deleted it from the ALDH signal peptide and precursor protein. The 19-amino acid signal peptide of ALDH, to which has been added 3 residues at the C terminus and from which has been deleted the 3-residue flexible linker region, has been studied by two-dimensional NMR in a dodecylphosphocholine micelle. In this membrane-like environment the peptide contains a single alpha-helical segment that extends almost the entire length of the peptide. NH exchange experiments show residues on the hydrophobic face of the peptide to exchange much more slowly than those of the hydrophilic face. Combined with the previous study, these results suggest that precursor protein import simply requires a sufficiently long amphiphilic helix (or helices) to bind stably to the membrane. The N and C helices of native ALDH are only about 6-8 residues long; this represents only about two turns of a helix, and either helix on its own does not provide enough stabilization to ensure folding and binding to the membrane. The linker-deleted ALDH peptide contains a single helix of 12-14 residues that is long enough to provide a hydrophobic surface that can stably interact with the hydrophobic interior of the membrane. The function of the C helix in the native signal peptide is therefore to enhance the stability and binding of the N-terminal signal to the membrane. Significantly, unlike native ALDH precursor protein, the linker-deleted signal peptide precursor protein could no longer be processed after import into mitochondria. As explained by modeling of the alpha-helix and the NH exchange rate data, the precursor protein requires that the first several residues of the mature protein be part of the hydrophobic membrane associated face of the helix.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
268
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
19906-14
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Import, processing, and two-dimensional NMR structure of a linker-deleted signal peptide of rat liver mitochondrial aldehyde dehydrogenase.
pubmed:affiliation
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.